Glare reducing rough surfaces

ABSTRACT

An intraocular lens for insertion into a capsular bag in order to focus incoming light toward a retina and process for manufacturing thereof along with concomitant reduced glare and improved vision provides for a center lens portion of a lens for focusing incoming light toward the retina and the surrounding lens portion for mounting the lens within the capsular bag. A surface roughness disposed on the surrounding lens portion is provided for reducing the glare due to non-focused light directed toward the retina from the intraocular lens with the roughness having a roughness level of between about Ra 45 and about Ra 350.

The present invention generally relates to apparatus and methods forimproving vision of an eye with a cataractic lens. More particularly,the present invention relates to an intraocular lens for insertion intoa capsular bag in order to focus incoming light toward a retina andstill more particularly relates to a process of fabricating anintraocular lens, which includes roughening portions of the lens inorder to reduce glare due to non-focused light directed toward theretina from the intraocular lens.

A typical intraocular lens (IOL) is formed from a suitable syntheticmaterial, such as silicone, and shaped for insertion into an eye. TheIOL may be utilized in place of, or, in addition to, the natural lens ofthe eye to correct vision. Often the IOL replaces the natural lens inthe capsular bag after removal of the natural lens.

A number of different types of IOL's have been developed for correctingvarious types of vision disorders.

While most IOL's are suitable for correcting visual disorders, they alsotypically cause the recipient to experience undesirable side effectscommonly referred to as “glare”.

This glare has been described as an arc, or pattern, with concentratedintensity and high local contrast. That is, the glare is a brightenedpattern which is easily distinguished by the recipient over other imagesprojected onto a retina by the lens. Accordingly, to reduce this glareperception, both the glare pattern intensity and the local contrast mustbe reduced below vision recognizable or perception thresholds.

Often, these glare effects which may be perceived as haloes, arcs oflight, flashing of light, as well as shadows are often caused byperipheral edges of the implanted IOL.

Specifically designed IOL edges have proved to be very effective onreducing edge glare phenomenon. Rounded edges have proved to be able toreduce glare perception by breaking the glare light concentration of aspecific pattern and thereby decreasing the glare pattern averageintensity and local contrast.

Of particular importance in that regard is disclosed in U.S. Pat. No.6,468,306 to Paul, Brady, and Deacon. This patent is incorporated in itsentirety into the present application by this specific referencethereto. This design hereinafter may be referred to as OptiEDGE(Advanced Medical Optics, Santa Ana, Calif.) has been successfullydesigned to reduce edge glare. For instance, a rounded transitionsurface on the anterior side of the peripheral edge diffuses theintensity of reflected light, or a particular arrangement of straightedge surfaces refracts the light so as not to reflect, or does notreflect at all.

It has also been found and reported in U.S. Pat. No. 6,162,249 that theuse of frosting, or roughening areas of the IOL can reduce glare. Inthis regard, the basic concept is the use of a roughened surface toavoid internally reflecting rays from causing the unwanted visual glare.

The present invention is directed to a process for fabricating a surfaceon an intraocular lens to provide optimum roughening thereof to producea random scattering surface finish. In that regard, the presentinvention also encompasses an intraocular lens utilizing that thesurface, a method for reducing glare from an intraocular lens onto aretina and ultimately a method for improving vision of an eye.

SUMMARY OF THE INVENTION

An intraocular, lens in accordance with the present invention forinsertion into a capsular bag, is provided for focusing incoming lighttoward a retina. The lens generally includes a center lens portion forfocusing incoming light toward the retina and a surrounding lens portionfor mounting the lens within the capsular bag.

A surface roughness disposed on the surrounding lens portion is providedfor reducing glare due to non-focused light directed toward the retinafrom the intraocular lens. The surface roughness has roughness level ofbetween about Ra 45 and about Ra 350.

In accordance with an embodiment of the present invention, the surfaceroughness is produced by Electrical Discharge Machining and thesurrounding lens portion comprises silicone.

More particularly, it has been found that a roughness level of about Ra180 is particularly suitable for reducing glare. The surface roughnessmay be disposed on anterior and posterior surfaces of the surroundinglens portion and selected portions having the provided surface roughnessmay include at least one haptic for fixing a lens within the capsularbag.

Preferably, the surrounding lens portion includes a peripheral edgesurface intersecting at least one of the anterior and a posteriorsurface to form a corner therebetween and a surface roughness, orfrosting, is disposed on the anterior and posterior surfaces other thanthe corner.

Also in accordance with the present invention, a process for fabricatinga surface on an intraocular lens is provided with the process comprisingroughening a smooth lens surface by Electrical Discharge Machining to aroughness level of between about Ra 45 and about Ra 350.

In addition, the present invention provides for a process of fabricatingan intraocular lens which includes providing a blank lens having acenter lens portion and a surrounding lens portion and roughening thesurrounding lens portion by electrical discharge machining to aroughness level of between about Ra 45 and about Ra 350.

Ultimately, the present invention provides a method for improving visionof an eye with a cataractic lens with the method including the steps ofremoving a cataractic lens from the lens capsule and inserting anintraocular lens into the capsule with the intraocular lens including acenter lens portion for focusing incoming light toward the retina, asurrounding lens portion for mounting the lens within the capsular bagand a surface roughness disposed on the surrounding lens portion forreducing glare due to non-focused light directed toward the retina fromthe intraocular lens. The surface roughness has a roughness level ofbetween about Ra 45 and about Ra 350.

Likewise, the present invention comprises using the method taught forphakic lenses and contemplates all of the disclosed steps with removalof the lens or during a “clear lens-ectomy” or procedure without removalof a cataractous or “cloudy” lens.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be betterunderstood by the following description when considered in conjunctionwith the accompanying drawings in which:

FIGS. 1 a and 1 b are representations of intraocular lenses which may beproduced in accordance with the present invention having a center lensportion for focusing incoming light toward a retina (not shown inFIG. 1) and a surrounding lens portion for mounting a lens within acapsular bag (not shown in FIG. 1);

FIG. 2 is an enlarged end view of the surrounding lens portion shown inFIG. 1 with a surface roughness disposed thereon;

FIG. 3 is a diagram of light at incident angles from 0 to 70° showingpassage through a cornea/lens and corresponding edge glares produced;

FIG. 4 is a diagram illustrating the occurrence of reflected andtransmitted edge glare and resulting images on a retina;

FIG. 5 is a diagram illustrating the surrounding the lens portion shownin FIG. 2 and resulting glare from incident light at 35° and 55°incident angle;

FIG. 6 is an illustration of surface scattering with differentscattering probability models;

FIG. 7 is a schematic representation of Electrical Discharge Machineapparatus for producing the surface roughness;

FIG. 8 are microscopic views of surface roughness on the lens shown inFIGS. 1 and 2 with arithmetic mean roughness Ra varying from Ra 45 to Ra490;

FIG. 9 are analyzed results from sample surfaces having the averageroughness from Ra 45 to Ra 490 showing the scattering level as afunction of roughness;

FIG. 10 is a plot of distribution width sigma as a function of surfaceroughness with the data fitted to a Gaussian distribution model; and

FIG. 11 is a comparison of glare at 55° incident angle for theintraocular lens made in accordance with the present invention with aroughened edge having average roughness of Ra 180 with an identical lenswithout edge roughening, i.e., a clear lens.

DETAILED DESCRIPTION

With reference to FIGS. 1 a and 1 b, there is illustrated intraocularlenses (IOLS) 10, 10 a having center portions 12, 12 a for focusingincoming light toward the retina of an eye (not shown in FIG. 1) and asurrounding lens portion 14, 14 a which may include fixation members, orhaptics, 18, 18 a, 20, 20 a for fixing the lens 10, 10 a within acapsular bag (not shown in FIG. 1) in a conventional manner. The lenses10, 10 a may be formed from any suitable material such as, for example,silicone, poly(methylmetharylate) or other solid elastically deformablematerials formed from functional groups such as, but not limited tovinylic, acrylic, methacrylic groups, i.e. hybrid material.

As more clearly shown in FIG. 2, a surface roughness is disposed on thesurrounding lens portion anterior surface 24 for reducing glare due tonon-focused light directed toward the retina from the intraocular lens,as will be hereinafter discussed in greater detail. A posterior surface26 may also be roughened. As illustrated surrounding lens portion 14 mayinclude a corner 28 and no surface roughening is applied thereto.

The surface roughness has a roughness level of between about Ra 45 andabout Ra 350 and preferably about Ra 180. Surface roughness is thearithmetic mean roughness value which is calculated from the integral ofthe absolute value of peak or valley with respect to a centerline,according to standard methods.

With reference to FIG. 3, there is illustrated an intraocular lens 10for focusing incoming light through a cornea 32 toward a retina 36 aswell as glare caused by non-focused light 40 directed toward the retina36 from the intraocular lens 10 at various incident angles of theincoming light 30, namely 30°-70°.

FIG. 4 illustrates the glare patterns 44; 46 on the retina 36 at a 40°incident angle of incoming light. Reflected light, illustrated by theline 50, causes an arcuate pattern curved toward the source of lightwhile incoming light at 42° incident angle produces non-focused light,indicated by the line 52, due to transmitted light which produces theglare pattern 46 which is curved away from the source.

FIG. 5 illustrates simulated glare from the lens 10 without the surfaceroughness at incident light angles of 35° and 55° on an S140e lens(Advanced Medical Optics, Santa Ana, Calif.).

The present invention provides for a roughened surface 24 on thelens-surrounding portion 14 as shown in FIG. 2 to provide a randomscattering surface. With a random scattering surface, the glare patternsare effectively reduced or eliminated, that is, glare is not perceiveddue not only to reduction in glare intensity but also in a reduction ofglare contrast. In other words, random light scattering provides auniform contrast level on the retina which does not include contrastedglare patterns as hereinbefore discussed.

A discussion of random scattering is useful in understanding the presentinvention. A random scattering surface can be modeled at the surfacewith uniform scattering in all directions in an ideal case such as aLambertian Scattering Surface shown in FIG. 6.

FIG. 6 shows an illustration of the probability distribution of such ascattering model. However, a practical surface usually is moreaccurately modeled as a surface that scatters light in Gaussiandistribution relative to the spectacular ray which is either thereflective ray or transmitted ray.

FIG. 6 also gives the probability curve for Gaussian scatteringdistribution. When the distribution width sigma is very large (thatis >1) the surface is close to a uniform scattering surface, whereaswhen the distribution width sigma is very narrow (<0.1) the surface isclose to an optical surface.

The distribution amplitude represents a scattering level at a specificscattering direction. It is the ratio of all energy associated to thescattered rays to the total energy associated to all reflected ortransmitted rays. The larger the scattering level the more energyassociated with the scattering ray.

The intraocular lens 10 and the surface roughness, or frosting, 24provided thereon is fabricated by providing a blank lens, preferablysilicone, having the center lens portion 12 and surrounding lens portion14 and thereafter roughening the surrounding lens portion 14 byElectrical Discharge Machining utilizing apparatus 60 diagramed in FIG.7.

Generally, the Electronic Discharge Machining apparatus 60 includes anelectrode tool 62, a slide table 64, and a work piece 66 for supportingthe intraocular lens 10 (not shown in FIG. 7). A pulse generator 70provides a voltage differential between the electrode tool 62 and workpiece 66 which is driven by a programmable circuit 72.

In a simplistic description of one mode of operation, the lens 10, 10 ais disposed on the work piece and the pulsed generator and slide tablemanipulated to provide the roughness 24 on the lens 10, 10 a to aspecified surface roughness Ra. As a specific example a program usableon an Electrical Discharge Machine available at Porex Medical Productsin Ontario, Calif. is set forth in Table 1 for providing a Ra 180surface on silicone lenses 10, 10 a as indicated by the surface 24 shownin FIG. 2.

FIG. 8 shows magnified photographs of surfaces having average surfaceroughness levels, or topographies, from Ra 45 to Ra 490 and programssimilar to that shown in Table 1 may be utilized for the production ofthe surfaces.

Example

Six IOL's having an edge roughness 26 from Ra 45 to Ra 490 weresubjected to scattering measurements at 35° and 55° incident lightangles with the light of 514 nm and 633 nm, respectively.

TABLE 1 MACHINING PROGRAM FOR Ra 180 ROUGHENING ON SILICONE   “;”“    (******************************************************);”“     (AMO SPARE TIRE TO A 180.+−15 RA FINISH 1/22/2003);”“    (******************************************************);”“     (2003/01/23 VERSION 8.2 CLRFLXB Column with bottom);”“    (******************************************************);”“     (2003/01/24, VERSION 8.2 SPARETIR Column with bottom);” “;” “(    PL ON OFF IP SV S UP DN JS LNS STEP  V HP PP C ALV OC LF JM LSLNM);” “C005 = + 0040 0065 004.4 055 02 008 040 010 0001 0.00000 02 00000 0 0018 0015 0000 01 02 303;” “C006 = + 0020 0030 003.0 060 02 008 040010 0001 0.00000 02 000 10 0 0018 0013 0000 01 03 303;” “C029 = + 00160025 002.4 060 02 008 040 010 0001 0.00000 02 000 10 0 0012 0013 0000 0103 303;” “;” “H005 = + 00000.00013 (123:RGH.S-FIN.FIN,1:RGH,13:RGH.FIN,);” “ (12:RGH.S-FIN,2:S-FIN,23:S-FIN.FIN,3:FIN );” “H017 = + 00000.00000(1:COMBINATION );” “H002 = − 00000.01830 (MACHINING DEPTH );” “H011 = +00000.00555 (EL1 UNDER SIZE );” “H012 = + 00000.00555 (EL2 UNDER SIZE);” “H013 = + 00000.00555 (EL3 UNDER SIZE );” “H027 = + 00000.02500(COLLISION AVOIDANCE POSITION );” “H010 = + 00000.00003 (EL PROCESS NO.);” “H028 = + 00000.00158 (SIDE OFFSET );” “H030 = + 00000.00252 (BOTTOMOFFSET );” “H048 = + 00000.00004 (CONDITION COUNT );” “H018 = +00000.00303 (LNM );” “H019 = + 00000.00001 (LNS );” “H000 = +00000.10000 (Projected area );” “H003 = + 00000.01250 (ACTUAL DEPTH );”“H008 = + 00000.50501 (CONDITION );” “H009 = + 00000.00030 (TIMER );”“H001 = + 00000.00000 (MACHINING DIRECTION );” “H007 = + 00000.00000(ABS/INC );” “H006 = + 00000.01401 (SIDE MACHINING AREA );” “H025 = +00000.00059 (SIDE ESCAPE );” “H026 = + 00000.00079 (BOTTOM ESCAPE );”“H032 = + 00000.00000 (LORAN ROTATION );” “;” “G90;” “H900=H027 H940=0H941=0 H942=3 H950=1 H951=0 H952=0 H910=0 H947=0 H960=0;” “G24;”“IFH005=3(1100);” “IFH005=23(1110);” “IFH005=2(1110);” “JUMP1120;”“N1100 H942=3;” “G83 Z920;” “JUMP2300;” “N1110 H942=2;” “G83 Z920;”“JUMP2200;” “N1120;” “G83 Z920;” “;” “N2200;” “N2300;” “QATP(54, 1, 0,3, 1, 0.00000, 0.00000, 1.00000, 0.00000, H027, 030);” “CRT(-EL3-COND1-HOLE1 -);” “M98P2001;” “QATP(54, 1, 0, 3, 1, 0.00000, 0.00000,1.00000, 0.00000, H027, 030);” “CRT(- EL3-COND2-HOLE1 -);” “M98P2002;”“QATP(54, 1, 0, 3, 1, 0.00000, 0.00000, 1.00000, 0.00000, H027, 030);”“CRT(- EL3-COND3-HOLE1 -);” “M98P2003;” “QATP(54, 3, 0, 3, 2, 0.00000,0.00000, 1.00000, 0.00000, H027, 030);” “CRT(- EL3-COND1-HOLE2 -);”“M98P2001;” “QATP(54, 3, 0, 3, 2, 0.00000, 0.00000, 1.00000, 0.00000,H027, 030);” “CRT(- EL3-COND2-HOLE2 -);” “M98P2002;” “QATP(54, 3, 0, 3,2, 0.00000, 0.00000, 1.00000, 0.00000, H027, 030);” “CRT(-EL3-COND3-HOLE2 -);” “M98P2003;” “QATP(54, 5, 0, 3, 3, 0.00000, 0.00000,1.00000, 0.00000, H027, 030);” “CRT(- EL3-COND1-HOLE3 -);” “M98P2001;”“QATP(54, 5, 0, 3, 3, 0.00000, 0.00000, 1.00000, 0.00000, H027, 030);”“CRT(- EL3-COND2-HOLE3 -);” “M98P2002;” “QATP(54, 5, 0, 3, 3, 0.00000,0.00000, 1.00000, 0.00000, H027, 030);” “CRT(- EL3-COND3-HOLE3 -);”“M98P2003;” “;” “N2400;” “G90 G00 M05 ZH920;” “IF H027=99999999(2401);”“G00 ZH027;” “JUMP2402;” “N2401;” “G81 Z+;” “N2402;” “IF H017=1(9999);”“IFH005=1(2410);” “IFH005=2(2410);” “IFH005=12(2410);” “JUMP9999;”“N2410;” “CRT(EL CHANGE);” “JUMP9999;” “;” “N2001;” “C005;” “H010=3H030=0.00610 H028=0.00311 H048=2 H009=10;” “G85 TH009;” “M98 P3300;”“M99;” “N2002;” “C006;” “H010=3 H030=0.00402 H028=0.00173 H048=3H009=20;” “G85 TH009;” “M98 P3300;” “M99;” “N2003;” “C029;” “H010=3H030=0.00252 H028=0.00158 H048=4 H009=30;” “G85 TH009;” “M98 P3300;”“M99;” “;” “(01FEB2002 V3.00 111);” “N3100 (*************** PATTERN 1***************);” “G83R923;” “IF H923=2(,3110);” “M99    (***** DELETEM99 : FULL DRY RUN *****);” “N3110;” “IF H002<H920(3120);”“H030=0-H030;” “H026=0-H026;” “N3120;” “M98 P3500;” “;” “M98 P3600;”“JUMP 3900;” “;” “N3200  (*************  PATTERN 2 3  *************);”“N3300;” “G83R923;” “IF H923=2(,3210);” “M99    (***** DELETE M99 : FULLDRY RUN *****);” “N3210;” “IF H002<H920(3220);” “H030=0-H030;”“H026=0-H026;” “N3220;” “M98 P3500;” “M98 P3600;” “JUMP 3900;” “;”“N3500 (********   PARAMETER IS SET UP **********);” “G24;” “LNMH018LNSH019 LP0000;” “G83UP918;” “QALEC(H000,H003,H008,H018,H019,1);” “N3530     ( **   WITH ROTATION   ** );” “IF H960=0(3550);” “G83 U947;”“LAH032+H947;” “G326;” “M99;” “N3550;” “LAH032;” “G326;” “M99;” “;”“N3600(*************   MACHINING   **************);” “G90+H007;” “IFH048<>1(3610);” “STEP0         ( **   1ST MACH.  ** );” “G01 Z+H002+H030M04;” “N3610;” “IF H048>800(,3660);” “N3620      ( ** TIMER MACHINING **);” “IF H000<10./25.4*1./25.4*1.(3660);”“QTIMER(H000,H006,H009,0.254/1000.,0);” “N3630 G85 ZH909   (**  FOR SIDE ** );” “STEP0+H[010+H010]−H028;” “G01 Z+H002+H030+H026 M04;” “N3640;”“QTIMER(H000,H006,H009,0.254/1000.,1);” “N3650 G85 ZH909  ( ** FORBOTTOM ** );” “STEP0+H[010+H010]−H028−H025;” “JUMP3670;” “N3660       (** FROM 2ND MACH ** );” “STEP0;” “IFH[010+H010]−H028<0.004/25.4*1.(3670);” “STEP0+H[010+H010]−H028;”“N3670;” “G01 Z+H002+H030 M04;” “G90;” “M99;” “;” “N3900 (*************  READ TIME   *************);” “G327;” “UPH918;” “G83 T[300+H952];”“H[301+H952]=99999;” “IF H952>100(3999);” “H952=H952+1;” “M99;” “N3999;”“H952=0;” “M99;” “N9999;”

From the measured scattering results, it has been found that all surfacescattering follow a Gaussian distribution by fitting the measured datato a Gaussian scattering model, as shown in FIG. 9, which is a plot ofscattering level versus average roughness.

Measured scattering level is about 0.993, as shown, and, as shown inFIG. 10 the distribution width sigma ranges from 0.4 to 1.5 with Ra 180having the maximum. A fitting correlation R² values for all cases areabove 0.95. Accordingly, the Ra 180 surface has found to have the bestscattering ability, is closest to random scattering.

In view of variation of distribution width sigma shown in FIG. 10, thisresult could not be predicted on the basis of the roughness Ra value.That is, there is no predictable connection, or correlation, between Raand scattering effectiveness.

FIG. 11 shows simulated comparison examples of the scattering analysisdone on the lens 10 with and without (clear) a roughness of Ra 180 at55° incident light angle. Defrosted (Lambertian) means the peripheralanterior area 24 and slope edge 28 are frosted with a uniform(Lambertian model) scattering surface finished with 0.9 scattering leveland frosted (Gaussian) means the peripheral area of the IOL interiorsurface 24 and the IOL slope edge 28 are frosted with a non-uniform(Gaussian model) scattering surface with 0.9 scattering level at 1.4half distribution sigma width.

The corresponding glare pattern average intensity and local contrast ofthe lenses is shown in Table 2

TABLE 2 The corresponding glare pattern average intensity and localcontrast of cases in FIG. 11. Clariflex Clear Lambertian GaussianAverage Intensity 1.04 × 10⁵ 0.62 × 10⁴ 0.75 × 10⁴ Local Contrast 0.880.02 0.08

It should be apparent that the results for the frosted lenses as shownin FIG. 11 illustrate an almost a uniform contrast with no discernmentof glare patterns as is evidenced with the clear lens.

Although there has been hereinabove described a specific glare reducingrough surfaces in accordance with the present invention for the purposeof illustrating the manner in which the invention may be used toadvantage, it should be appreciated that the invention is not limitedthereto. That is, the present invention may suitably comprise, consistof or consist essentially of the recited elements. Further, theinvention illustratively disclosed herein suitably may be practiced inthe absence of any element which is not specifically disclosed herein.Accordingly, any and all modifications, variations or equivalentarrangements which may occur to those skilled in the art, should beconsidered to be within the scope of the present invention as defined inthe appended claims.

1. An intraocular lens, comprising: a center lens portion for focusingincoming light toward the retina of an eye; a surrounding lens portion;and a rough surface disposed on the surrounding lens portion, the roughsurface having a surface roughness level of about Ra 180 μin, the roughsurface roughness having a Gaussian distribution width sigma of at least1 when illuminated by an incident light beam, and scattering data fromthe illuminated rough surface is fitted to a Gaussian distributionmodel, the incident light beam having a wavelength of 633 nanometers andilluminating the surface at a 55 degree incident light angle. 2-3.(canceled)
 4. The lens according to claim 1 wherein the intraocular lensis made of a solid elastically deformable material selected from a groupconsisting of silicone, acrylic and hybrid materials.
 5. (canceled) 6.The lens according to claim 1 wherein the surface roughness is disposedon anterior and posterior surfaces of the surrounding lens portion. 7.The process according to claim 1 wherein selected portions of thesurrounding lens portion are roughened.
 8. The lens according to claim 1further comprising at least one haptic coupled to the surrounding lensportion.
 9. The lens according to claim 1 wherein the surrounding lensportion includes a peripheral edge surface intersecting at least one ofan anterior and a posterior surface wherein the rough surface isdisposed on the peripheral edge surface.
 10. A process of fabricating anintraocular lens comprising: providing a blank lens having a center lensportion and a surrounding lens portion; and roughening the surroundinglens portion such that the surrounding lens portion has a rough surfacewith a surface roughness level of about Ra 180 μin; the rough surfacehaving a Gaussian distribution width sigma of at least 1 whenilluminated by an incident light beam, and scattering data from theilluminated rough surface is fitted to a Gaussian distribution model,the incident light beam having a wavelength of 633 nanometers andilluminating the surface at a 55 degree incident light angle. 11-12.(canceled)
 13. The process according to claim 10 wherein selectedportions of the surrounding lens portion are roughened.
 14. The processaccording to claim 10 wherein roughening the surrounding lens portioncomprises roughening a selected area by Electrical Discharge Machining.15. The process according to claim 14 wherein the roughening of thesurrounding lens portion further comprises controlling the ElectricalDischarge Machining through a program as set forth in Table 1.